Valve bag

ABSTRACT

A valve bag comprising a back wall and a front wall made of first and second panels partially overlapping each other, said front and back walls being joined along their entire periphery, the first panel having at least two plies and the second panel projecting between the plies of said first panel, and a transverse seal at a distance from the top end of the bag uniting the two panels in their common area of overlap and defining between said second panel and the plies of the first panel a tubular self-closing opening extending transversely of the bag adjacent the top thereof, said panels in their common area of overlap being also united along at least one line extending from the transverse seal to the bottom of the bag, said tubular opening being of such diameter and being so located transversely of the bag as to allow insertion therethrough of a filling spout and free delivery of filling material from said spout.

1 l 1 3,746,246 [451 July 17, 1973 VALVE BAG [75] Inventor:CharlesRobertson Murray,Toronto,

Ontario, Canada [73] Assignee: Canadian Industries Limited,

Montreal, Quebec, Canada [22] Filed: Dec. 22, 1971 [21] Appl. No.:210,835

2,895,387 7/1959 Robinson et al.. 229/625 3,22l,789 l2/1965 Harding229/625 X 3,394,871 7/1968 Williams et al. 229/625 PrimaryExaminer-Samuel B. Rothberg Assistant Examiner-Stephen P. GarbeAttorney-Guy Drouin [57] ABSTRACT A valve bag comprising a back wall anda front wall made of first and second panels partially overlapping eachother, said front and back walls being joined along their entireperiphery, the first panel having at least two plies and the secondpanel projecting between the plies of said first panel, and a transverseseal at a distance from the top end of the bag uniting the two panels intheir common area of overlap and defining between said second panel andthe plies of the first panel a tubular self-closing opening extendingtransversely of the bag adjacent the top thereof, said panels in theircommon area of overlap being also united along at least one lineextending from the transverse seal to the bottom of the bag, saidtubular opening being of such diameter and being so located transverselyof the bag as to allowinsertion therethrough of a filling spout and freedelivery of filling material from said spout.

5 Claims, 2 Drawing Figures Patented July 17, 1973 VALVE BAG Thisinvention relates to a plastic valve bag suitable for manufacture byautomatic bag making equipment in line with a plastic film extrusionprocess.

Valve bags are in general used for packaging materials such asfertilizers and cement. These bags possess the important commercialadvantage of easy filling through a valve structure and self-closing ofthis valve structure after filling. However, the presence of the valvein the bag structure introduces problems in bag manufacture. In plasticbags suitable for the industrial packaging and shipping of powdered orgranular products, the valve flap normally consists of a section of thesame thickness as that of the main bag wall for providing valve strengthand of a thinner flexible membrane for providing the required anti-siftcharacteristics. The complexity of the equipment required toautomatically produce and insert this type of valve configuration hasbeen a major drawback in automatic plastic valve bag manufacture.

It has now been found that a valve bag can be provided which has itsvalve constructed of overlapping panels in the front wall of the bag andwhich can be manufactured employing automatic bag making equipment.

It is therefore the primary object of this invention to provide a valvebag which can be readily and automatically manufactured and which isfree of the abovedescribed disadvantages inherent in prior art valvebags. Additional objects of the invention will appear hereinafter.

The valve bag in accordance with the invention comprises a back wall anda front wall made of first and second panels partially overlapping eachother, said front and back walls being joined along their entireperiphery, the first panel having at least two plies and the secondpanel projection between the plies of said first panel and a transverseseal at a distance from the top end of the bag uniting the two panels intheir common area of overlap panel and defining between said second andthe plies of the first panel a tubular self-closing opening extendingtransversely of the bag adjacent the top thereof, said panels in theircommon area of overlap being also united together alone at least oneline extending from said tubular opening to the bottom of the bag, saidtubular opening being of such diameter and being so located transverselyof the bag as to allow insertion therethrough of a filling spout andfree delivery of filling material from said spout.

The invention is illustrated in the accompanying drawings wherein:

FIG. I is an elevational view of a two-ply valve bag constructed inaccordance with the principles of the present invention, and

FIG. 2 is a sectional view along line II-II of FIG. 1.

In the particular embodiment illustrated in the drawings, a generallyrectangular pillow case type bag is shown having a two-ply back wall 11and a front wall made of two-ply partially overlapping panels 12 and 13.Panels 12 and 13 are integral with back wall 11 at their opposed sideedges 14 and 15 and form with said back wall a flattened two-ply tubewhich is closed at both ends by transverse seals 16 and 17. As isclearly shown in FIG. 2, the overlap between panels 12 and 13 is of aspecial type in that the free edge of panel 12 is telescoped between theinner ply 18 and the outer ply l9 of panel 13. For reasons which willbecome apparent hereinafter, the inner ply 18 of panel 13 is preferablyalthough not necessarily somewhat wider than the outer ply l9. Extendingfrom transverse seal 17 to a line extending generally transversely ofthe bag and at a distance from transverse seal 16 which defines the topof the bag, are seal 20 near the free edge of ply 18 of panel 13 unitingsaid ply 18 with the two plies of panel 12 and seal 21 near the freeedge of panel 12 uniting all the plies of both panels 12 and 13. Afurther seal 22 extending to a point short of the top extremity of seal21 is provided near the free edge of the ply 19 also uniting all pliesof panels 12 and 13. The portion left unsealed in the common area ofoverlap of panels 12 and 13 adjacent the top end of the bag constitutesa tubular valve opening suitable for insertion of a filling spout notshown.

When it is desired to fill the bag, a filling spout is introduced intothe bag through the tubular valve by first inserting it between panel 12and outer ply 19 of panel 13 and thence between panel 12 and inner ply18 of panel 13. As should be readily apparent, seal 22 is shorter thanseal 21 in order to make the filling spout insertion easier. It shouldbe understood, however, that this is a preferred embodiment and thatseal 22 can be as long as seal 21. To reinforce the side of the tubularvalve opposite the top end of the bag it has been found advantageous toprovide generally transverse seals 23 and 24. Such seals which are shownas continuous need not be so and can be replaced by dot seals or mazeseals. Seals 20, 21 and 22 also shown as continuous, can be alsoreplaced by maze seals.

It should be understood that the combination of seals 20, 21, 22, 23 and24, particularly illustrated in the drawings, is not critical and can bereplaced, for instance, by a seal having the configuration of aninverted L extending from the bottom of the bag in the common area ofoverlap between panel 12 and plies l8 and 19 of panel 13 and thentransversely of the bag to the free edge of ply 18.

While in the drawings, the valve opening is shown as being locatedsubstantially close to one side of the bag, it should be understood thatit can be located anywhere adjacent transverse seal 16, provided thatsufficient space is left between it and the side edges of the bag toallow insertion of a reasonably long filling spout and free delivery offilling material therefrom. It is thus seen that the location of thevalve opening transversely of the bag may vary with the width of thebag. Generally, it has been found suitable to locate the valve openingwithin the vertical half of the bag opposite the vertical side of thebag facing the inner mouth of the valve opening.

To facilitate insertion of a filling spout through the valve into thebag, it is preferable that the extent of overlap between outer ply l9and panel 12 be rather limited. It should be readily seen that with thispreferred arrangement it is easier to lift the unsealed portion of outerply 19 with the filling spout, then reach the free edge of panel 12 andfinally insert the spoutbetween inner ply l8 and panel 12. It is for thesame reason that transverse seal 24 is inclined such as illustrated inFIG. 1.

The particular two-ply bag shown in the drawings is preferablyfabricated from a tubing of appropriate transverse dimension, saidtubing being seamless and consisting of a film of a thermoplasticresinous material. Any heat sealable thermoplastic resinous material orplastic sheet material sealable by heat, hot melt adhesive, a compatibleadhesive, combinations of adhesives and tapes, etc. may be used toconstruct the bag of the invention. Among all those materials thepreferred one, for reasons which are readily apparent to those versed inthe art, is polyethylene.

In making the bag, a flattened tubing is continuously fed to a bagmaking machine where one wall of the tubing is slit longitudinally closeto one fold and that fold is thereafter flattened. A longitudinallyfolded web results having one ply somewhat wider than the other, whichis then passed over a suitable A-frame where it is further foldedlongitudinally to form a double ply tubing adapted to form back wall 11and overlapping panels 12 and 13 of the bag. The common area of overlapbetween panels 12 and 13 is provided at regular longitudinal intervalswith seals 20, 21 and 22 as well as with seals 23 and 24. The double plytubing is finally transversely sealed and cut at regular intervals toprovide bags such as shown in the drawings.

As best shown in FIG. I, it is preferred that seals 20, 21 and 22stopshort of and thus do not intersect with transverse seal 17 at thebottom of the bag. The reason for this is that the intersection of seals20, 21 and 22 with seal 17 results in weakening of the latter seal atthe points of intersection and thus is weakening the bottom of the bag.

While the invention has been described in connection with a double plybag, it should be understood that the principles thereof are applicableto the fabrication of bags wherein the back wall 11 and panel 12 haveone or morethan two plies. The important feature in all such bags isthat panel 13 of the front wall 12 has at least two plies and that panel12 projects between the plies of panel 12.

What we claim is:

l. A valve bag comprising a back wall and a front wall made of first andsecond panels partially overlap-.

ping each other, said front and back walls being joined along theirentire periphery, the firstv panel having at least two plies and thesecond panel projecting between the plies of said first panel, and atransverse sea] at a distance from the top end of the bag uniting thetwo panels in their common area of overlap and defining between saidsecond panel and the plies of the first panel a tubular self-closingopening extending transversely of the bag adjacent the top thereof, saidpanels in their common area of overlap being also united along at leastone line extending from the transverse seal to the bottom of the bag,said tubular opening being of such diameter and being so locatedtransversely of the bag as to allow insertion therethrough of a fillingspout and free delivery of filling material from said spout.

2. A valve bag as claimed in claim 1 wherein the back wall and first andsecond panels of the front wall each have two plies.

3. A valve bagas claimed in claim 1 wherein the plies of the first panelwhich are located externally of the second panel are narrower than theplies which are located internally of said second panel.

4. A valve bag as claimed in claim 1, wherein the bag is constructed ofheat scalable plastic film.

5. A valve bag as claimed in claim 1, wherein the bag is constructed ofpolyethylene film.

1. A valve bag comprising a back wall and a front wall made of first andsecond panels partially overlapping each other, said front and backwalls being joined along their entire periphery, the first panel havingat least two plies and the second panel projecting between the plies ofsaid first panel, and a transverse seal at a distance from the top endof the bag uniting the two panels in their common area of overlap anddefining between said second panel and the plies of the first panel atubular self-closing opening extending transversely of the bag adjacentthe top thereof, said panels in their common area of overlap being alsounited along at least one line extending from the transverse seal to thebottom of the bag, said tubular opening being of such diameter and beingso located transversely of the bag as to allow insertion therethrough ofa filling spout and free delivery of filling material from said spout.2. A valve bag as claimed in claim 1 wherein the back wall and first andsecond panels of the front wall each have two plies.
 3. A valve bag asclaimed in claim 1 wherein the plies of the first panel which arelocated externally of the second panel are narrower than the plies whichare located internally of said second panel.
 4. A valve bag as claimedin claim 1, wherein the bag is constructed of heat sealable plasticfilm.
 5. A valve bag as claimed in claim 1, wherein the bag isconstructed of polyethylene film.